1. Field of the Invention
This invention relates to a stabilized polyphenylene ether resin composition, and particularly, to a polyphenylene ether resin composition thermally stabilized with a substituted dicarboxylic acid dihydrazide.
2. Description of the Prior Art
Polyphenylene ether resins have excellent mechanical properties and electrical properties and high heat distortion temperatures, but are susceptible to oxidation. In other words, polyphenylene ether resin is easily subjected to degradation by heat and ultraviolet rays, particularly the thermal stability is very low in the presence of oxygen and when exposed to high temperatures in air, the resin is easily colorized and becomes fragile. The low thermal stability of polyphenylene ether resins results in scorch such as colorization and lowered physical characteristics. The uses of polyphenylene ether resins are limited to a great extent by the low thermal stability.
Heretofore, there have been reported various methods for stabilizing polyphenylene ether resins. This drawback of polyphenylene ether is generally considered due to the terminal hydroxy group in the terminal group of the polymer and substituents to the benzene rings, and therefore, there has been proposed a method of stabilizing polyphenylene ether resins comprising protecting the terminal groups by acylation, but this stabilizing method is not only complicated, but also the stabilizing effect is not satisfactory. There have been proposals to add thermal stabilizing agents, but a satisfactory one has not yet found.